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Re: Topband: 160m portable operating

To: Top Band group <>
Subject: Re: Topband: 160m portable operating
From: steve d <>
Date: Tue, 11 Sep 2007 09:51:30 -0700 (PDT)
List-post: <>
Hi All, I was at my friend's new property over the weekend operating in the VHF 
contest so I got to scope out the place. 
  There are lots of tall trees, I would say in the neighborhood of 60'.  That 
would be plenty to string up an inverted L. The other option would  be to raise 
my aluminum tent pole mast as high as I can get it (could  go up 70-75'). As 
someone pointed out before, ground radials are going  to be the only option 
since 1/8w (to get away from ground coupling) is  60 some feet on 160 - thats 
as high as the trees. How many  radials  should I put out? I know the more the 
better, but there  has to be a point where performence vs. number of radials is 
decent  enough to not go further. 
  Heres where I am with the rx antenna idea: There is space for  beverages, and 
there should be plenty of time to set everything up. I  would like to center 
the feedpoint, that way I have 1 feedline going  out there. I will also need a 
control cable for the switchbox as well  as DC feed (can combine that in to the 
control cable) for the preamp (I  could run that through the coax, but Im not a 
big fan of that method).  I am not sure what the dimensions of the property 
are, Ill have to  investigate this further. The issue I might run in to is 
there wont be  enough space from the center out to string up a decent size 
beverage.  In this case, I might need multiple feedpoints - which would cost 
more  $$ (more cable, more preamps, more impedance matchers).
  Another issue is the location of the transmitting antenna vs. the  location 
of the beverages. As the idea stands, the transmitting antenna  is going to be 
in between the beverages.
  What length should I be consitering for a decent beverage? 500-800'?  How 
about grounding them? I know I need a ground rod at each end and a  terminating 
resistor at the far end. What is the best way to go about  figuring out the 
termination resistance? Can I use some kind of pot to  be able to adjust it, or 
should I figure out what the resistance should  be and put resistors in?
  The next question is how many should I lay out? If the beamwidth is  10deg (I 
think thats what they are, around there) then, to get all  directions I would 
need 36. When you factor in the cost of the wire,  relays for switching, ground 
rods, and resistors.. hmm, thats a LOT of  $$. Are there any directions I 
should really concentrate on? Europe,  Africa, South America, Australia, Asia? 
Im sure I can eliminate the  majority of that 36 by focusing on a few good 
locations, rather than  trying to accomodate everything. 
  I still have plenty of time to think about this HI. Ive just got my wheels 
spinning right now. 
  Steve, KC8QVO
Pinpoint customers who are looking for what you sell. 
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